A radiation diagnostic apparatus such as an X-ray CT (Computed Tomography) apparatus, an X-ray angiographic apparatus, and an X-ray diagnostic apparatus includes a radiation detector configured to detect X-rays which have been radiated from an X-ray source and have passed through an object. In general, plural radiation detecting elements are arranged in a radiation detector. A radiation detector with multiple radiation detecting elements arranged therein is quite useful because it can detect a wide range of X-rays.
A radiation diagnostic apparatus equipped with a radiation detector in which plural radiation detecting elements are arranged acquires all output data outputted by all of the radiation detecting elements of the radiation detector in X-ray imaging of an object. However, output data of detecting element whose position is corresponding to a region other than an imaging region of the object (hereinafter, the region other than the imaging region is referred to as a non-observing region) are unnecessary data excluding a case where the output data corresponding to the non-observing region are required (e.g., a case where such data are used in post-processing).
Thus, it has to be said that it is a waste of electric power to acquire output data of detecting elements corresponding to the non-observing region, unless the output data of such detecting elements are required.